refactor: enhance nullability annotations and improve code safety across multiple files

Author: jamesmcroft

src/MADE.Collections/Compare/GenericEqualityComparer{T}.cs

@@ -43,6 +43,11 @@ public GenericEqualityComparer(Func<T, object> comparison)
     /// <exception cref="T:System.Exception">The <see cref="Comparison"/> callback throws an exception.</exception>
     public bool Equals(T? x, T? y)
     {
+        if (x == null || y == null)
+        {
+            return x == null && y == null;
+        }
+
         object first = this.Comparison.Invoke(x);
         object second = this.Comparison.Invoke(y);
 

src/MADE.Collections/DictionaryExtensions.cs

@@ -31,6 +31,7 @@ public static class DictionaryExtensions
     /// </typeparam>
     /// <exception cref="T:System.ArgumentNullException">The <paramref name="dictionary"/> or <paramref name="key"/> is <see langword="null"/>.</exception>
     public static void AddOrUpdate<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key, TValue value)
+        where TKey : notnull
     {
         ArgumentNullException.ThrowIfNull(dictionary);
         ArgumentNullException.ThrowIfNull(key);
@@ -52,18 +53,17 @@ public static void AddOrUpdate<TKey, TValue>(this Dictionary<TKey, TValue> dicti
     /// <param name="key">The key to get a value for.</param>
     /// <param name="defaultValue">The default value to return if not exists. Default, null.</param>
     /// <returns>The value if it exists for the key; otherwise, null.</returns>
-    public static TValue GetValueOrDefault<TKey, TValue>(
+    public static TValue? GetValueOrDefault<TKey, TValue>(
         this Dictionary<TKey, TValue> dictionary,
         TKey key,
-        TValue defaultValue = default)
+        TValue? defaultValue = default)
+        where TKey : notnull
     {
-        var result = defaultValue;
-
-        if (dictionary != null && dictionary.ContainsKey(key))
+        if (dictionary != null && dictionary.TryGetValue(key, out var result))
         {
-            result = dictionary[key];
+            return result;
         }
 
-        return result;
+        return defaultValue;
     }
 }

src/MADE.Collections/ObjectModel/ObservableItemCollection{T}.cs

@@ -144,13 +144,27 @@ public void RemoveRange(IEnumerable<T> items)
     /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
     /// </summary>
     public void Dispose()
+    {
+        this.Dispose(true);
+        GC.SuppressFinalize(this);
+    }
+
+    /// <summary>
+    /// Releases unmanaged and optionally managed resources.
+    /// </summary>
+    /// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
+    protected virtual void Dispose(bool disposing)
     {
         if (this.disposed)
         {
             return;
         }
 
-        this.ClearItems();
+        if (disposing)
+        {
+            this.ClearItems();
+        }
+
         this.disposed = true;
     }
 
@@ -178,11 +192,19 @@ protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
         switch (e.Action)
         {
             case NotifyCollectionChangedAction.Add:
-                this.RegisterPropertyChangedEvents(e.NewItems);
+                if (e.NewItems != null)
+                {
+                    this.RegisterPropertyChangedEvents(e.NewItems);
+                }
+
                 break;
             case NotifyCollectionChangedAction.Remove:
             case NotifyCollectionChangedAction.Replace:
-                this.UnregisterPropertyChangedEvents(e.OldItems);
+                if (e.OldItems != null)
+                {
+                    this.UnregisterPropertyChangedEvents(e.OldItems);
+                }
+
                 if (e.NewItems != null)
                 {
                     this.RegisterPropertyChangedEvents(e.NewItems);
@@ -223,11 +245,11 @@ private void UnregisterPropertyChangedEvents(IEnumerable items)
         }
     }
 
-    private void OnItemPropertyChanged(object sender, PropertyChangedEventArgs e)
+    private void OnItemPropertyChanged(object? sender, PropertyChangedEventArgs e)
     {
         this.CheckDisposed();
         this.ItemPropertyChanged?.Invoke(
             this,
-            new ObservableItemCollectionPropertyChangedEventArgs(sender, this.IndexOf((T)sender), e));
+            new ObservableItemCollectionPropertyChangedEventArgs(sender!, this.IndexOf((T)sender!), e));
     }
 }

src/MADE.Data.Converters/DateTimeToStringValueConverter.cs

@@ -25,7 +25,7 @@ public class DateTimeToStringValueConverter : IValueConverter<DateTime, string>
     /// </returns>
     public string Convert(DateTime value, object? parameter = default)
     {
-        string format = parameter?.ToString();
+        string? format = parameter?.ToString();
         return !string.IsNullOrWhiteSpace(format)
                    ? value.ToString(format, CultureInfo.InvariantCulture)
                    : value.ToString(CultureInfo.InvariantCulture);

src/MADE.Data.Converters/Extensions/StringExtensions.cs

@@ -61,7 +61,7 @@ public static string Truncate(this string value, int maxLength)
         }
 
         const string suffix = "...";
-        return value.Substring(0, maxLength - suffix.Length) + suffix;
+        return string.Concat(value.AsSpan(0, maxLength - suffix.Length), suffix);
     }
 
     /// <summary>
@@ -96,7 +96,7 @@ public static string ToDefaultCase(this string value)
     /// <param name="value">The string value to convert.</param>
     /// <param name="encoding">The encoding to get the value bytes while converting.</param>
     /// <returns>The Base64 string representing the value.</returns>
-    public static string ToBase64(this string value, Encoding encoding = default)
+    public static string ToBase64(this string value, Encoding? encoding = default)
     {
         encoding ??= Encoding.UTF8;
         return Convert.ToBase64String(encoding.GetBytes(value));
@@ -108,7 +108,7 @@ public static string ToBase64(this string value, Encoding encoding = default)
     /// <param name="base64Value">The Base64 value to convert.</param>
     /// <param name="encoding">The encoding to get the value string while converting.</param>
     /// <returns>The string value representing the Base64 string.</returns>
-    public static string FromBase64(this string base64Value, Encoding encoding = default)
+    public static string FromBase64(this string base64Value, Encoding? encoding = default)
     {
         encoding ??= Encoding.UTF8;
         return encoding.GetString(Convert.FromBase64String(base64Value));

src/MADE.Data.EFCore/EntityBase{TKey}.cs

@@ -16,7 +16,7 @@ public abstract class EntityBase<TKey> : IEntityBase<TKey>
     /// Gets or sets the identifier of the entity.
     /// </summary>
     [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
-    public TKey Id { get; set; }
+    public TKey Id { get; set; } = default!;
 
     /// <summary>
     /// Gets or sets the date of the entity's creation.

src/MADE.Data.EFCore/Extensions/DbContextExtensions.cs

@@ -35,7 +35,7 @@ public static async Task UpdateAsync<T>(
         T entity,
         CancellationToken cancellationToken = default)
     {
-        context.Update(entity);
+        context.Update(entity!);
         await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
     }
 

src/MADE.Data.Serialization/Json/Converters/JsonTypeMigrationConverter.cs

@@ -32,7 +32,7 @@ public class JsonTypeMigrationConverter : JsonConverter<object>
     /// To add migrations, call the <see cref="AddTypeMigration"/> method.
     /// </remarks>
     public JsonTypeMigrationConverter()
-        : this(null)
+        : this(Array.Empty<JsonTypeMigration>())
     {
     }
 
@@ -42,7 +42,7 @@ public JsonTypeMigrationConverter()
     /// <param name="migrations">The type migrations to initialize with.</param>
     public JsonTypeMigrationConverter(params JsonTypeMigration[] migrations)
     {
-        if (migrations != null && migrations.Any())
+        if (migrations != null && migrations.Length > 0)
         {
             this.migrations.AddRange(migrations);
         }
@@ -60,7 +60,7 @@ public void AddTypeMigration(JsonTypeMigration migration)
 
         lock (this.migrationLock)
         {
-            JsonTypeMigration existingMigration = this.migrations.FirstOrDefault(
+            JsonTypeMigration? existingMigration = this.migrations.FirstOrDefault(
                 m =>
                     m.FromAssemblyName == migration.FromAssemblyName &&
                     m.FromTypeName == migration.FromTypeName);
@@ -85,11 +85,14 @@ public override object Read(ref Utf8JsonReader reader, Type typeToConvert, JsonS
 
         if (root.ValueKind == JsonValueKind.Object && root.TryGetProperty("$type", out JsonElement typeElement))
         {
-            string typeString = typeElement.GetString();
-            resolvedType = this.ResolveType(typeString) ?? typeToConvert;
+            string? typeString = typeElement.GetString();
+            if (typeString != null)
+            {
+                resolvedType = this.ResolveType(typeString) ?? typeToConvert;
+            }
         }
 
-        return root.Deserialize(resolvedType, this.GetInnerOptions(options));
+        return root.Deserialize(resolvedType, this.GetInnerOptions(options))!;
     }
 
     /// <inheritdoc/>
@@ -110,13 +113,13 @@ private JsonSerializerOptions GetInnerOptions(JsonSerializerOptions options)
         return this.innerOptions;
     }
 
-    private Type ResolveType(string typeString)
+    private Type? ResolveType(string typeString)
     {
         int commaIndex = typeString.IndexOf(',');
         string typeName = commaIndex >= 0 ? typeString[..commaIndex].Trim() : typeString.Trim();
-        string assemblyName = commaIndex >= 0 ? typeString[(commaIndex + 1)..].Trim() : null;
+        string? assemblyName = commaIndex >= 0 ? typeString[(commaIndex + 1)..].Trim() : null;
 
-        JsonTypeMigration migration;
+        JsonTypeMigration? migration;
         lock (this.migrationLock)
         {
             migration = this.migrations.FirstOrDefault(

src/MADE.Data.Serialization/Json/JsonTypeMigration.cs

@@ -18,8 +18,8 @@ public class JsonTypeMigration
     /// <param name="toType">The type being migrated to.</param>
     public JsonTypeMigration(Type fromType, Type toType)
     {
-        this.FromAssemblyName = fromType.Assembly.GetName().Name;
-        this.FromTypeName = fromType.FullName;
+        this.FromAssemblyName = fromType.Assembly.GetName().Name ?? string.Empty;
+        this.FromTypeName = fromType.FullName ?? string.Empty;
         this.ToType = toType;
     }
 

src/MADE.Data.Validation/Validators/Base64Validator.cs

@@ -48,7 +48,7 @@ public override void Validate(object value)
         }
         else
         {
-            base.Validate(value);
+            base.Validate(value!);
         }
 
         this.IsDirty = true;